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Thread: Can Cooler 4000

  1. #31

    Default Re: Can Cooler 4000


  2. #32
    London Lad's Avatar
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    Default Re: Can Cooler 4000

    Dave, you are clearly nuts as a fruit cake! (and also a genius)
    Last edited by London Lad; 06-01-2018 at 02:21 AM. Reason: Corrected silly mistake!


  3. #33

    Default Re: Can Cooler 4000





    Holy Cow! The Can Cooler 4000 works. It started out at about 4 minutes but now looks like we might be able to go under 2 minutes after some changes. The following is some detail of how the first tests performed and how it is evolving.


    Starting out during our initial 4 minute runs, the machine cooled the center of the diet coke to 41 degrees with about a ¼ inch of ice caked all the way around the inside sides of the can. If you then take the can out of the machine and swirl it by hand for a few seconds it quickly cools all the liquid down to 33 degrees F (0 degrees C). But we do not want ice.


    The initial power supply settings:
    Voltage: 12V
    Current: 9A
    Starting conditions (time zero):
    Copper heat sinks : 68 degrees F
    Water or coke: 68 degrees F
    End conditions (time 4 minutes):
    Copper heat sinks : 84 degrees F
    Water or coke: 33 degrees F



    Ice is a better thermal conductor than water but it hurts our cause. The copper/aluminum are much better at transferring the heat away from the water directly. So we tried another experiment. We opened the top of the soda can filled it with water and stirred the liquid with a chopstick while it was cooling. This gets all of the water to 34 degrees in 2 minutes 30 seconds and almost no ice!


    Starting conditions (time zero):
    Copper heat sinks: 67 degrees F
    Water or coke: 67 degrees F
    End conditions (time 2:00):
    Copper heat sinks: 75 degrees F
    Water or coke: 40 degrees F
    End conditions (time 2:30):
    Copper heat sinks: 78 degrees F
    Water or coke: 34 to 32 degrees F (minimal ice)


    In these tests we are not running anywhere near 4000W, we do not know the optimal settings yet and are playing it safe. In other previous tests we had the current turned up to 12A (17V). But back then we did not know it was creating ice in the can so quickly. When the ice forms the cold plate temperature goes way down and the whole system slows down. There is a balance point we need to find with the current applied to the Peltier chips based on the delta- T of the system. Too much power in and the efficiency goes down.


    Agitating the liquid is essential. But, we do not want to mix the liquid by hand so the machine needs to agitate the liquid itself. I did realize this beforehand and that is why we have the option for powered mecanum wheels. Unfortunately, I now know they will not be enough. Especially after we turn up the power. So we are off redesigning the can cooler. This is a major redesign but the cooling engines are not being changed, only their support structure.


    My hope is to cool a can to 35 degrees in under 120 seconds. To achieve this, we are going to cut about 33% of the copper mass out of the cold plates. That will reduce 2lb of copper that need not be cooled. We are going to turn up the power to find the optimum value. And last we are going to agitate the liquid.


    It looks like the best way to mix an unopened can is to roll it or rotate it around its long axis with that axis aligned horizontal. So I will be rotating the cooling engines around an axis that is horizontal. This sketch shows the structure. A four jaw scroll chuck will be inside at the center to actuate the four arms simultaneously. A rotational armature will connect the power to the engines.



    Cheers
    Dave
    Last edited by Data; 06-01-2018 at 10:02 AM.

  4. #34
    nfetterly's Avatar
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    Default Re: Can Cooler 4000

    We just got rid of my university mini-fridge that I bought 36 years ago and replaced it with a 2 year old full size fridge. Don't know which one is more efficient, but there is alot of cold beer & coke zero in this house.


  5. #35

    Default Re: Can Cooler 4000

    Those numbers are unbelievable.

    • 12 volts
    • 9 amps
    • 4 minutes


    That is 7.2 watt hours of energy or 26k joules.

    • 60 kg of copper
    • 68F (20C) for copper at start
    • 84F (29C) for sinks at end
    • 0.385 joules/gram C specific heat of copper


    The copper was heated by 208k joules.

    • 340 grams of water
    • 68F (20C) for water at start
    • 33F (0.6C) for water at end
    • 4.2 joules/gram C specific heat of water


    The water cooled by 27k joules.

    See what I mean about unbelievable? No way so little electricity could produce so much heat restively. I think you might have left something out..... Perhaps the 12V and 9A was per supply and you have 8 supplies running? So it was really 12 volts at 54 amps. Then it is 208k joules of electricity which makes a lot more sense. And it would cost 0.63¢ of electricity per firing

    I'm very surprised that the peltiers were able to work at all with a 28C delta.
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  6. #36

    Default Re: Can Cooler 4000



    I finished the CAM and Mike finished machining the mecanum wheel hub.

    A little background: I wanted the can cooler 4000 to be on wheels in my bar so I can push it in the corner when it is not in use. It is going to be over 300 lb and so you cannot move it otherwise. Also I was thinking of motorizing it so it could shake the liquid. That part is not going to be necessary because it will be rotating. However, it may still be fun to motorize it just to see the mecanum wheels do there magic. We will see. . .

    I got this particular mecanum wheel design off one of those pay to download CAD sites. I could have drawn it myself and in fact I had to almost completely redrew it anyway. As most of you know I use Inventor for CAD. My Hypermill CAM runs inside of Inventor. It took about 20 job steps to cut each hub boss on the inclined fixture. You are indexing it around by hand to do all six locations then you flip it over and run six more times. Only three more wheels to go. I think we will bead blast the hub when it is done. Mike and I went to the local metal scrap yard where everything is $1.60 per lb and got the aluminum for the rollers. I wanted to use polyurethane or nylon for the rollers but aluminum won out due to my super smooth floor and the weight of the entire device.

    Cheers
    Dave

  7. #37

    Default Can Cooler 4000

    Dave- I feel you will have better success agitating with the can rotation speeding up, then slowing down and stopping, speeding up, then slowing down and stopping again and again during the cooling cycle. This will ensure the aluminum can and the liquid inside are almost always rotating at different rates providing ideal agitation.

    If the spin comes up to speed and then continues at one set speed for the entire duration of the cooling cycle, the liquid may end up spinning at the same speed as the can or very close to it, reducing the actual amount of agitation and movement of the liquid inside relative to the aluminum can.

    Also I feel that varying the rotational speed to help agitation would remove the need for a horizontal spin axis. I understand the air bubble inside forces the liquid inside to rotate in an out of round pattern when the fan is sideways, and that helps agitation, but I feel designing for a horizontal spin axis makes things much more complex.

    Simplicity is the ultimate sophistication.

    I hope that idea helps if you hadn't thought of that already.
    Last edited by InvisibleFrodo; 06-02-2018 at 06:52 PM.

  8. #38

    Default Re: Can Cooler 4000

    Expanding on InvisibleFrodo's comment: another way to prevent the can and liquid from moving in lockstep would be to use oscillating agitation. Oscillating has the additional benefit of not needing slip rings that are rated for 60 amps
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  9. #39

    Default Re: Can Cooler 4000

    Quote Originally Posted by InvisibleFrodo View Post
    Dave- I feel you will have better success agitating with the can rotation speeding up, then slowing down and stopping, speeding up, then slowing down and stopping again and again during the cooling cycle. This will ensure the aluminum can and the liquid inside are almost always rotating at different rates providing ideal agitation.


    If the spin comes up to speed and then continues at one set speed for the entire duration of the cooling cycle, the liquid may end up spinning at the same speed as the can or very close to it, reducing the actual amount of agitation and movement of the liquid inside relative to the aluminum can.


    Also I feel that varying the rotational speed to help agitation would remove the need for a horizontal spin axis. I understand the air bubble inside forces the liquid inside to rotate in an out of round pattern when the fan is sideways, and that helps agitation, but I feel designing for a horizontal spin axis makes things much more complex.


    Simplicity is the ultimate sophistication.


    I hope that idea helps if you hadn't thought of that already.
    Your suggestions and insight are spot on. Thanks.


    Mixing liquid in a smooth rotating horizontal cylindrical container with an air bubble works well at a constant RPM if the liquid breaks from the upper region. Vortices will form through to the center of the liquid depending on the geometry and RPM. The RPM will be slow enough to enable the separation. There are of course very effective ice powered can coolers that use this principle. However, I am not going to leave this to chance. I plan to test the mixing performance and that includes your idea of varying the RPM. Maybe I should build a transparent test rig? I agree simplicity is important. A four jaw scroll chuck will be needed to hold the spinning copper arms pushed into the can regardless of its orientation. It has to be leaned over by 90 degrees for the mixing air bubble to work. If you have the can upright you only get laminar flow in the can with limited to no vortices and reaching the center would be diminished. I will see what I can come up with and post here with the results.

    Edit: Also, accelerating and decelerating such a huge rotating inertia is not easy. I am searching for a solution that is quiet with a rubber timing belt drive. Timing belts only because I happen to have lots of them and the pulleys in my junk parts.

    Cheers
    Dave
    Last edited by Data; 06-04-2018 at 05:24 PM.

  10. #40
    karlthev's Avatar
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    Default Re: Can Cooler 4000

    Uh Dave, this is a refrigerator....right? Shore don't look like my Sears Super Special 'frig somehow....

    Sorry for the intrude, I'm going back to my "room" now....


    Karl

  11. #41

    Default Re: Can Cooler 4000

    Here is a very short animation on the new design.



    Oops, no, not that one, this one . . .



    We have redesigned the Can Cooler 4000. Mixing the liquid during the cooling process mitigates the thermal gradient and ice buildup. When completed, it will spin the can in a horizontal attitude yielding a nearly complete internal mixing of the beverage. I put together this short computer animation from my CAD so everybody can see what the new device is going to look like. We already have more than half of the parts made so it will not be too long before we get to give it a spin. Also, not shown in the video is the redesigned cold plate that will lower its combined weight from 3 lbs to 2 lbs. As the soda weight is 3/4 lbs, that should be about a 15 second reduction (10%) to the overall cooling time. The .75 lbs of water takes about .75 BTU/F and the 2 lbs of copper takes about .2 BTU/F.

    Mike has a video of the scroll chuck case spinning on its big bearings. I will post it here.


    Cheers
    Dave

  12. #42

    Default Re: Can Cooler 4000




    This will get buried inside the can cooler and be used as a mechanism to simultaneously open the 4 arms holding the cooling engines.

    cheers
    dave



  13. #43

    Default Re: Can Cooler 4000

    Fun with Peltier chips . . .




    Last edited by Data; 07-01-2018 at 10:04 PM.

  14. #44

    Default Re: Can Cooler 4000

    This is the main case that will hold the cooling engines.


  15. #45

    Default Re: Can Cooler 4000

    This is a video of the water mixing test at 24 RPM. The paper only floats for a few minutes so I mixed them fresh and ran the test. I think the wood is heavier than water but not till all the micro air bubbles inside the paper are released. 96 RPM worked better but I do not know if it is necessary.





    This is a view of the test setup.





    Cheers
    Dave
    Last edited by Data; 07-02-2018 at 01:41 PM.

  16. #46
    Flashaholic* dizzy's Avatar
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    Default Re: Can Cooler 4000

    I've been missing stuff, haven't I.... This is literally, too cool! A fitting cool fall project, for sure.
    The beatings will continue until morale improves!!!!

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